soporific

UK: /ˌsɒpəˈrɪfɪk/ US: /ˌsɑpəˈrɪfɪk/ ,(sop′ə rif′ik, sō′pə-)

WordReference Random House Learner's Dictionary of American English © 2025

sop•o•rif•ic /ˌsɑpəˈrɪfɪk/   adj. 

1. Drugs Also, sop•o•rif•er•ous /ˌsɑpəˈrɪfərəs/ . causing sleep:
   a soporific drug.

n. [countable]

2. something that causes sleep, as a medicine or drug:
   slipped a soporific into her drink.

WordReference Random House Unabridged Dictionary of American English © 2025

sop•o•rif•ic  (sop′ə rif′ik, sō′pə-), adj. 

1. Drugs causing or tending to cause sleep.
2. Drugs pertaining to or characterized by sleep or sleepiness;
   sleepy;
   drowsy.

n. 

3. something that causes sleep, as a medicine or drug.

• Latin sopor sopor + -i- + -fic; compare French soporifique
• 1655–65

sop′o•rif′i•cal•ly, adv. 

Collins Concise English Dictionary © HarperCollins Publishers::

soporific / ˌsɒpəˈrɪfɪk/ adjective
also: soporiferous

1. inducing sleep
2. drowsy; sleepy

noun

1. a drug or other agent that induces sleep